1. Field of the Invention
The present invention relates to a temperature compensation apparatus for a camera and, more particularly, to a temperature compensation apparatus for performing temperature compensation for a camera whose characteristics change with the ambient temperature.
2. Description of the Related Art
Recently, with the widespread use of molded parts for a camera body and the like, the positional relationship of the optical components of a camera has been greatly influenced by temperature. For example, the refractive index of a plastic lens or the like, which is increasingly used nowadays, changes with temperature. For this reason, the focal point of the lens may be greatly shifted depending on the ambient temperature, and a high-quality photograph cannot be obtained.
Under the circumstances, a technique has been developed to obtain high-quality photographs (for example, Published Unexamined Japanese Patent Application Nos. 57-64204 and 1-288806). In this technique, the ambient temperature is measured in advance, and focus adjustment with temperature compensation is performed.
Temperature compensation is applied to other techniques. For example, since a load torque in a film wind-up operation changes with temperature, a driving voltage to a film wind-up motor is changed in accordance with temperature. Furthermore, in order to make the contrast of a liquid crystal element constant with respect changes in temperature, a voltage applied to the liquid crystal element is changed in accordance with temperature. In order to eliminate the influences of temperature, it is very important to accurately measure the ambient temperature.
As described above, for a proper operation of a camera, the ambient temperature must be accurately measured. As a method of measuring the ambient temperature, a method is disclosed (e.g., Published Unexamined Japanese Patent Application No. 57-64204), in which a temperature-measuring resistive element such as a thermistor is arranged near a member requiring temperature compensation to measure the ambient temperature.
If, however, the ambient temperature is to be measured by using such a temperature-measuring resistive element, the following disadvantages are posed. In an apparatus having limitations in terms of space and cost, such as a camera in which reductions in size and cost are important, it is not desirable to store a temperature measuring unit constituted by a temperature measuring resistive element and associated elements. Such an arrangement is not desirable also in terms of cost.